This analysis of the United States health care system reviews developments in organization and governance, health financing, health care provision, health reforms, and health system performance. The U.S. system has both considerable strengths and notable weaknesses. It has a large and well-trained health workforce, a wide range of high-quality medical specialists as well as secondary and tertiary institutions, a robust health sector research program, and, for selected services, among the best medical outcomes in the world. But it also suffers from incomplete coverage of its citizenry, health expenditure levels per person far exceeding all other countries, poor objective and subjective indicators of quality and outcomes, and an unequal distribution of resources and outcomes across the country and among different population groups. Because of the adoption of the Affordable Care Act in 2010, and subsequent revisions to it, the U.S. is facing a period of enormous change. There is a great need to improve coverage and improve equity, better ensure quality outcomes, and find ways to better control expenditures. Health Systems in Transition: USA provides an in-depth discussion of these issues and a thorough review of the U.S. health care system.